The present invention relates to a high efficiency hydraulic system for delivering pressurized hydraulic fluid to a hydraulic actuator, and to a pump suitable for use in such a system.
In one type of conventional hydraulic system, a gear pump is used to pressurize hydraulic fluid and to direct the pressurized hydraulic fluid to a hydraulic actuator such as a cylinder used to perform work. Once the cylinder completes its cycle (either extension or retraction), hydraulic fluid from the pump is bypassed to the supply tank of the pump or is directed to the opposite side of the cylinder piston for the return stroke. Because the supply tank is at low pressure, it is necessary for the pump again to develop the full working pressure required for the cylinder to perform its function during the next cycle.